Am currently refreshing my entire intake, fuel lines and pressure regulator and wanted to see what the latest thinking is on fuel injectors? My engine is stock and I plan to keep it that way for the foreseeable future. Simply get the OEM ones refurbed and cleaned or is there a better replacement to be had? I read something about a 4 outlet spray pattern versus the oem single but don’t know if that’s hype or meaningfully better.

 

I have had these guys refurbish my injectors. On two 964s now You get before and after reports

https://www.witchhunter.com

 

Yes there are drop in 4-hole replacements available. I asked this of the folks who cleaned my injectors and sent me a spray video - I was somewhat shocked to see the stream not spray that a single hole injector makes. The conclusion I came to is that its not worth the upgrade for its own sake but if you need injectors anyway I would consider it in lieu of refurbing. Here is what they told me:

patterns mentioned here https://sssquid.com/v3/ssshop/injector-refurbishment/

"there are dozens of direct swap injectors with the quad-hole nozzle. Some may require a tune if their specifications is too far off from the tune you're running. Assuming the tune you're running is designed for the ~17 Lb/hr injectors you sent us, you'll want to keep your flow rate within 10% and make sure you have a well-working EGO sensor, or you'll want a tune for the injectors you'll be changing to."

Some popular options are:

0-280-156-346 (14.5@3) modern plastic body stock replacement (alt PN: 62415)
0-280-155-703 (17@3)
0-280-155-744 (19@3)
0-280-155-746 (19@3)
0-280-155-771 (18.2@3)

You can view more flow ratings here: https://www.sssquid.com/v3/injector-flow-ratings/

 

Russ. Of that list- which are closest to OEM?

 

I don't know Rob - I didn't pursue it further.

 

I’m sure not all 4 hole injectors are equal. There are many videos available showing the atomization of Bosch Generation 3 injectors and it is not a stream.


Someone here had a good observation and question if the atomization is worth it when the 964 injector is pointed at the wall vs the valve.

Now with the 993 intake chimneys repointing the injector at the valve, there may be some benefits. I have heard of someone plugging these in without retuning: Bosch 0280155884

964 (Scope through injector hole)



993

 

Yes all above is correct, I also asked some chip makers if they often tuned for 4-hole injectors and that said its not common to do for its own sake but they've seen it done when someone needs radically different flow rates etc.

 

I don’t have any before and after experience switching, but from tuning cars in the past I speculate the benefits are more for idle stabilization, cold starts, and fuel efficiency with it becoming more noticeable the larger injector you get.

 

I had my OEM injectors cleaned and refurbed and that already made a huge difference. Smoother, more power. Now that I’m tearing the whole fuel system apart and redoing all the lines and the FPR thought it worth asking but from what people are saying sounds like just sticking with my refurbed injectors is the answer!

 

for reference i found this awesome chart on bosch fuel injectors but part number and has all their characteristics. i'm also debating swapping injectors. if i keep it within the 10% as stated above as well as 4 hole pattern i think it would work without a retune. plus you can get them refurbished on ebay for under $100 for the set
warning - this chart is like a rabbit hole. it's had me clicking back and forth between screens long enough for my eyes to start stinging lol

http://users.erols.com/srweiss/tableifc.htm

 

Looks like you're on the West coast and likely have local options, but I always recommend https://injector-rehab.com as they have 24 hour turnaround, great reporting, and fair pricing.

 

As has been posted here previously, you may want to double-check the numbers on that site. The Bosch spec on the 964 injectors (0 280 150 731) is: 151.4g/min @ 3bar - 15.9Ohm which is 222.8cc/min.

 

I think there’s quite a bit to be gained from upgraded injectors, but it has to be accompanied by a tune. From what I understand, the 964 injectors are maxed out at ~300 hp, but 993 injectors are good for ~365. It would be interesting to hear from a tuner like Steve Wong regarding what sort of injector upgrades the stock ECU can support. My tuner, Stewart at TE Systems, has a package for 964 & 993 converting to upgraded injectors, ECU, and MAP sensor, but it’s not cheap (but still much less than Motec). Personally, I used 993 injectors on my first engine build, then Stewart’s newer Bosch units on my second.



TE Systems kit

My set-up

 

Moriarty- that's the only real way to do it

I have a chip that was setup to run larger injectors by a race shop. It was likely written for a race car without the usual daily driver tuning concerns. For daily reliability, it's kind of a mess. There is some code that I haven't deciphered, but what I do see is that the fuel tables are mostly just cranked down to compensate for the extra fuel volume. That's about it. The startup fuel tables aren't touched or anything else. And there are a *lot* of little fine tuning tables in the stock chip.

The chip is really built around the stock injectors. Even with identical flow injectors, you have to assume that the latency/dead time will be different. That means you get different air/fuel depending on if you're running a bunch of accessories to drop the running voltage (headlights, heater, defrost, windshield wipers, pumpin' stereo...) or not. Next up, the startup fueling is related to how well the fuel atomizes at colder temperatures, and how much fuel ends up just wetting the port walls.

The "latest on injectors" is the same as it always has been- you need a tune-able injection system to obtain any real benefit.

 

That looks interesting and looks true plug and play. Is it? Any comparisons to other tunes or chips?

I have a custom tune on mine, but I think I’d still like to modernize aspects of engine management even if it doesn’t give much more gains.